/* 
 * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
 * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
 *
 * Original author:
 *  David Clark <vdc1048 @ tx.rr.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
#include <pjmedia/wav_playlist.h>
#include <pjmedia/errno.h>
#include <pjmedia/wave.h>
#include <pj/assert.h>
#include <pj/file_access.h>
#include <pj/file_io.h>
#include <pj/log.h>
#include <pj/pool.h>
#include <pj/string.h>

#define THIS_FILE           "wav_playlist.c"

#define SIGNATURE           PJMEDIA_SIG_PORT_WAV_PLAYLIST
#define BYTES_PER_SAMPLE    2


#if 1
#   define TRACE_(x)    PJ_LOG(4,x)
#else
#   define TRACE_(x)
#endif

#if defined(PJ_IS_BIG_ENDIAN) && PJ_IS_BIG_ENDIAN!=0
    static void samples_to_host(pj_int16_t *samples, unsigned count)
    {
        unsigned i;
        for (i=0; i<count; ++i) {
            samples[i] = pj_swap16(samples[i]);
        }
    }
#else
#   define samples_to_host(samples,count)
#endif


struct playlist_port
{
    pjmedia_port     base;
    pj_pool_t       *pool;
    unsigned         options;
    pj_bool_t        eof;
    pj_uint32_t      bufsize;
    char            *buf;
    char            *readpos;

    pj_off_t        *fsize_list;
    unsigned        *start_data_list;
    unsigned        *data_len_list;
    unsigned        *data_left_list;
    pj_off_t        *fpos_list;
    pj_oshandle_t   *fd_list;       /* list of file descriptors */
    int              current_file;  /* index of current file.   */
    int              max_file;      /* how many files.          */

    pj_status_t    (*cb)(pjmedia_port*, void*);
    pj_bool_t        subscribed;
    void           (*cb2)(pjmedia_port*, void*);
};


static pj_status_t file_list_get_frame(pjmedia_port *this_port,
                                       pjmedia_frame *frame);
static pj_status_t file_list_on_destroy(pjmedia_port *this_port);


static struct playlist_port *create_file_list_port(pj_pool_t *pool,
                                                   const pj_str_t *name)
{
    struct playlist_port *port;

    port = PJ_POOL_ZALLOC_T(pool, struct playlist_port);
    if (!port)
        return NULL;

    /* Put in default values.
     * These will be overriden once the file is read.
     */
    pjmedia_port_info_init(&port->base.info, name, SIGNATURE,
                           8000, 1, 16, 80);

    port->base.get_frame = &file_list_get_frame;
    port->base.on_destroy = &file_list_on_destroy;

    return port;
}


static pj_status_t file_on_event(pjmedia_event *event,
                                 void *user_data)
{
    struct playlist_port *fport = (struct playlist_port*)user_data;

    if (event->type == PJMEDIA_EVENT_CALLBACK) {
        if (fport->cb2)
            (*fport->cb2)(&fport->base, fport->base.port_data.pdata);
    }
    
    return PJ_SUCCESS;
}


/*
 * Fill buffer for file_list operations.
 */
static pj_status_t file_fill_buffer(struct playlist_port *fport)
{
    pj_uint32_t size_left = fport->bufsize;
    pj_uint32_t size_to_read;
    pj_ssize_t size;
    pj_status_t status;
    int current_file = fport->current_file;

    /* Can't read file if EOF and loop flag is disabled */
    if (fport->eof)
        return PJ_EEOF;

    while (size_left > 0)
    {
        /* Calculate how many bytes to read in this run. */
        size = size_to_read = size_left;
        status = pj_file_read(fport->fd_list[current_file],
                              &fport->buf[fport->bufsize-size_left],
                              &size);
        if (status != PJ_SUCCESS)
            return status;
        
        if (size < 0)
        {
            /* Should return more appropriate error code here.. */
            return PJ_ECANCELLED;
        }

        if (size > (pj_ssize_t)fport->data_left_list[current_file]) {
            /* We passed the end of the data chunk,
             * only count the portion read from the data chunk.
             */
            size = (pj_ssize_t)fport->data_left_list[current_file];
        }
        
        size_left -= (pj_uint32_t)size;
        fport->data_left_list[current_file] -= (pj_uint32_t)size;
        fport->fpos_list[current_file] += size; 
        
        /* If size is less than size_to_read, it indicates that we've
         * encountered EOF. Rewind the file.
         */
        if (size < (pj_ssize_t)size_to_read)
        {
            /* Rewind the file for the next iteration */
            fport->fpos_list[current_file] = 
                fport->start_data_list[current_file];
            pj_file_setpos(fport->fd_list[current_file], 
                           fport->fpos_list[current_file], PJ_SEEK_SET);
            fport->data_left_list[current_file] = 
                                            fport->data_len_list[current_file];

            /* Move to next file */
            current_file++;
            fport->current_file = current_file;

            if (fport->current_file == fport->max_file)
            {
                /* Clear the remaining part of the buffer first, to prevent
                 * old samples from being played. If the playback restarts,
                 * this will be overwritten by new reading.
                 */
                if (size_left > 0) {
                    pj_bzero(&fport->buf[fport->bufsize-size_left], 
                             size_left);
                }

                /* All files have been played. Call callback, if any. */
                if (fport->cb2) {
                    pj_bool_t no_loop = (fport->options & PJMEDIA_FILE_NO_LOOP);

                    if (!fport->subscribed) {
                        status = pjmedia_event_subscribe(NULL, &file_on_event,
                                                         fport, fport);
                        fport->subscribed = (status == PJ_SUCCESS)? PJ_TRUE:
                                            PJ_FALSE;
                    }

                    if (fport->subscribed && fport->eof != 2) {
                        pjmedia_event event;

                        if (no_loop) {
                            /* To prevent the callback from being called
                             * repeatedly.
                             */
                            fport->eof = 2;
                        } else {
                            fport->eof = PJ_FALSE;
                            /* start with first file again. */
                            fport->current_file = current_file = 0;
                            fport->fpos_list[0] = fport->start_data_list[0];
                            pj_file_setpos(fport->fd_list[0],
                                           fport->fpos_list[0], PJ_SEEK_SET);
                            fport->data_left_list[0] = fport->data_len_list[0];
                        }

                        pjmedia_event_init(&event, PJMEDIA_EVENT_CALLBACK,
                                           NULL, fport);
                        pjmedia_event_publish(NULL, fport, &event,
                                          PJMEDIA_EVENT_PUBLISH_POST_EVENT);
                    }

                    /* Should not access player port after this since
                     * it might have been destroyed by the callback.
                     */
                    return (no_loop? PJ_EEOF: PJ_SUCCESS);

                } else if (fport->cb) {
                    PJ_LOG(5,(THIS_FILE,
                              "File port %.*s EOF, calling callback",
                              (int)fport->base.info.name.slen,
                              fport->base.info.name.ptr));
                    
                    fport->eof = PJ_TRUE;

                    status = (*fport->cb)(&fport->base,
                                          fport->base.port_data.pdata);

                    if (status != PJ_SUCCESS)
                    {
                        /* This will crash if file port is destroyed in the
                         * callback, that's why we set the eof flag before
                         * calling the callback:
                         fport->eof = PJ_TRUE;
                         */
                        return status;
                    }

                    fport->eof = PJ_FALSE;
                }


                if (fport->options & PJMEDIA_FILE_NO_LOOP)
                {
                    PJ_LOG(5,(THIS_FILE, "File port %.*s EOF, stopping..",
                              (int)fport->base.info.name.slen,
                              fport->base.info.name.ptr));
                    fport->eof = PJ_TRUE;
                    return PJ_EEOF;
                }
                else
                {
                    PJ_LOG(5,(THIS_FILE, "File port %.*s EOF, rewinding..",
                              (int)fport->base.info.name.slen,
                              fport->base.info.name.ptr));
                    
                    /* start with first file again. */
                    fport->current_file = current_file = 0;
                    fport->fpos_list[0] = fport->start_data_list[0];
                    pj_file_setpos(fport->fd_list[0], fport->fpos_list[0],
                                   PJ_SEEK_SET);
                    fport->data_left_list[0] = fport->data_len_list[0];
                }               
                
            } /* if current_file == max_file */

        } /* size < size_to_read */

    } /* while () */
    
    /* Convert samples to host rep */
    samples_to_host((pj_int16_t*)fport->buf, fport->bufsize/BYTES_PER_SAMPLE);
    
    return PJ_SUCCESS;
}


/*
 * Create wave list player.
 */
PJ_DEF(pj_status_t) pjmedia_wav_playlist_create(pj_pool_t *pool_,
                                                const pj_str_t *port_label,
                                                const pj_str_t file_list[],
                                                int file_count,
                                                unsigned ptime,
                                                unsigned options,
                                                pj_ssize_t buff_size,
                                                pjmedia_port **p_port)
{
    struct playlist_port *fport;
    pjmedia_audio_format_detail *afd;
    pj_off_t pos;
    pj_status_t status = PJ_SUCCESS;
    int index;
    pj_bool_t has_wave_info = PJ_FALSE;
    pj_str_t tmp_port_label;
    char filename[PJ_MAXPATH];  /* filename for open operations.    */
    pj_pool_t *pool = NULL;


    /* Check arguments. */
    PJ_ASSERT_RETURN(pool_ && file_list && file_count && p_port, PJ_EINVAL);

    /* Normalize port_label */
    if (port_label == NULL || port_label->slen == 0) {
        tmp_port_label = pj_str("WAV playlist");
        port_label = &tmp_port_label;
    }

    /* Be sure all files exist  */
    for (index=0; index<file_count; index++) {

        PJ_ASSERT_RETURN(file_list[index].slen >= 0, PJ_ETOOSMALL);
        if (file_list[index].slen >= PJ_MAXPATH)
            return PJ_ENAMETOOLONG;

        pj_memcpy(filename, file_list[index].ptr, file_list[index].slen);
        filename[file_list[index].slen] = '\0';

        /* Check the file really exists. */
        if (!pj_file_exists(filename)) {
            PJ_LOG(4,(THIS_FILE,
                      "WAV playlist error: file '%s' not found",
                      filename));
            return PJ_ENOTFOUND;
        }
    }

    /* Normalize ptime */
    if (ptime == 0)
        ptime = 20;

    /* Create own pool */
    pool = pj_pool_create(pool_->factory, port_label->ptr, 1024, 1024, NULL);
    PJ_ASSERT_RETURN(pool, PJ_ENOMEM);

    /* Create fport instance. */
    fport = create_file_list_port(pool, port_label);
    if (!fport) {
        PJ_PERROR(4,(THIS_FILE, PJ_ENOMEM, "WAV playlist create failed"));
        return PJ_ENOMEM;
    }

    fport->pool = pool;

    afd = pjmedia_format_get_audio_format_detail(&fport->base.info.fmt, 1);

    /* start with the first file. */
    fport->current_file = 0;
    fport->max_file = file_count;

    /* Create file descriptor list */
    fport->fd_list = (pj_oshandle_t*)
                     pj_pool_zalloc(pool, sizeof(pj_oshandle_t)*file_count);
    if (!fport->fd_list) {
        status = PJ_ENOMEM;
        goto on_error;
    }

    /* Create file size list */
    fport->fsize_list = (pj_off_t*)
                        pj_pool_alloc(pool, sizeof(pj_off_t)*file_count);
    if (!fport->fsize_list) {
        status = PJ_ENOMEM;
        goto on_error;
    }

    /* Create start of WAVE data list */
    fport->start_data_list = (unsigned*)
                             pj_pool_alloc(pool, sizeof(unsigned)*file_count);
    if (!fport->start_data_list) {
        status = PJ_ENOMEM;
        goto on_error;
    }

    /* Create data len list */
    fport->data_len_list = (unsigned*)
                             pj_pool_alloc(pool, sizeof(unsigned)*file_count);
    if (!fport->data_len_list) {
        status = PJ_ENOMEM;
        goto on_error;
    }

    /* Create data left list */
    fport->data_left_list = (unsigned*)
                             pj_pool_alloc(pool, sizeof(unsigned)*file_count);
    if (!fport->data_left_list) {
        status = PJ_ENOMEM;
        goto on_error;
    }

    /* Create file position list */
    fport->fpos_list = (pj_off_t*)
                       pj_pool_alloc(pool, sizeof(pj_off_t)*file_count);
    if (!fport->fpos_list) {
        status = PJ_ENOMEM;
        goto on_error;
    }

    /* Create file buffer once for this operation.
     */
    if (buff_size < 1) buff_size = PJMEDIA_FILE_PORT_BUFSIZE;
    fport->bufsize = (pj_uint32_t)buff_size;


    /* Create buffer. */
    fport->buf = (char*) pj_pool_alloc(pool, fport->bufsize);
    if (!fport->buf) {
        status = PJ_ENOMEM;
        goto on_error;
    }

    /* Initialize port */
    fport->options = options;
    fport->readpos = fport->buf;


    /* ok run this for all files to be sure all are good for playback. */
    for (index=file_count-1; index>=0; index--) {

        pjmedia_wave_hdr wavehdr;
        pj_ssize_t size_read;
        pj_off_t size_to_read;

        /* we end with the last one so we are good to go if still in function*/
        pj_memcpy(filename, file_list[index].ptr, file_list[index].slen);
        filename[file_list[index].slen] = '\0';

        /* Get the file size. */
        fport->current_file = index;
        fport->fsize_list[index] = pj_file_size(filename);

        /* Size must be more than WAVE header size */
        if (fport->fsize_list[index] <= (pj_off_t)sizeof(pjmedia_wave_hdr)) {
            status = PJMEDIA_ENOTVALIDWAVE;
            goto on_error;
        }
        
        /* Open file. */
        status = pj_file_open( pool, filename, PJ_O_RDONLY | PJ_O_CLOEXEC, 
                               &fport->fd_list[index]);
        if (status != PJ_SUCCESS)
            goto on_error;
        
        /* Read the file header plus fmt header only. */
        size_to_read = size_read = sizeof(wavehdr) - 8; 
        status = pj_file_read( fport->fd_list[index], &wavehdr, &size_read);
        if (status != PJ_SUCCESS) {
            goto on_error;
        }

        if (size_read != size_to_read) {
            status = PJMEDIA_ENOTVALIDWAVE;
            goto on_error;
        }
        
        /* Normalize WAVE header fields values from little-endian to host
         * byte order.
         */
        pjmedia_wave_hdr_file_to_host(&wavehdr);
        
        /* Validate WAVE file. */
        if (wavehdr.riff_hdr.riff != PJMEDIA_RIFF_TAG ||
            wavehdr.riff_hdr.wave != PJMEDIA_WAVE_TAG ||
            wavehdr.fmt_hdr.fmt != PJMEDIA_FMT_TAG)
        {
            TRACE_((THIS_FILE,
                "actual value|expected riff=%x|%x, wave=%x|%x fmt=%x|%x",
                wavehdr.riff_hdr.riff, PJMEDIA_RIFF_TAG,
                wavehdr.riff_hdr.wave, PJMEDIA_WAVE_TAG,
                wavehdr.fmt_hdr.fmt, PJMEDIA_FMT_TAG));
            status = PJMEDIA_ENOTVALIDWAVE;
            goto on_error;
        }
        
        /* Must be PCM with 16bits per sample */
        if (wavehdr.fmt_hdr.fmt_tag != 1 ||
            wavehdr.fmt_hdr.bits_per_sample != 16)
        {
            status = PJMEDIA_EWAVEUNSUPP;
            goto on_error;
        }
        
        /* Block align must be 2*nchannels */
        if (wavehdr.fmt_hdr.block_align != 
                wavehdr.fmt_hdr.nchan * BYTES_PER_SAMPLE)
        {
            status = PJMEDIA_EWAVEUNSUPP;
            goto on_error;
        }
        
        /* If length of fmt_header is greater than 16, skip the remaining
         * fmt header data.
         */
        if (wavehdr.fmt_hdr.len > 16) {
            PJ_CHECK_OVERFLOW_UINT32_TO_LONG(wavehdr.fmt_hdr.len-16,
                               status = PJMEDIA_ENOTVALIDWAVE; goto on_error;);
            size_to_read = (pj_off_t)wavehdr.fmt_hdr.len - 16;
            status = pj_file_setpos(fport->fd_list[index], size_to_read, 
                                    PJ_SEEK_CUR);
            if (status != PJ_SUCCESS) {
                goto on_error;
            }
        }
        
        /* Repeat reading the WAVE file until we have 'data' chunk */
        for (;;) {
            pjmedia_wave_subchunk subchunk;
            size_read = 8;
            status = pj_file_read(fport->fd_list[index], &subchunk, 
                                  &size_read);
            if (status != PJ_SUCCESS || size_read != 8) {
                status = PJMEDIA_EWAVETOOSHORT;
                goto on_error;
            }
            
            /* Normalize endianness */
            PJMEDIA_WAVE_NORMALIZE_SUBCHUNK(&subchunk);
            
            /* Break if this is "data" chunk */
            if (subchunk.id == PJMEDIA_DATA_TAG) {
                wavehdr.data_hdr.data = PJMEDIA_DATA_TAG;
                wavehdr.data_hdr.len = subchunk.len;
                break;
            }
            
            /* Otherwise skip the chunk contents */
            PJ_CHECK_OVERFLOW_UINT32_TO_LONG(subchunk.len, 
                               status = PJMEDIA_ENOTVALIDWAVE; goto on_error;);
            size_to_read = subchunk.len;

            status = pj_file_setpos(fport->fd_list[index], size_to_read, 
                                    PJ_SEEK_CUR);
            if (status != PJ_SUCCESS) {
                goto on_error;
            }
        }
        
        /* Current file position now points to start of data */
        status = pj_file_getpos(fport->fd_list[index], &pos);
        fport->start_data_list[index] = (unsigned)pos;
        fport->data_len_list[index] = wavehdr.data_hdr.len;
        fport->data_left_list[index] = wavehdr.data_hdr.len;
        
        /* Validate length. */
        if (wavehdr.data_hdr.len > fport->fsize_list[index] - 
                                       fport->start_data_list[index]) 
        {
            status = PJMEDIA_EWAVEUNSUPP;
            goto on_error;
        }
        if (wavehdr.data_hdr.len < ptime * wavehdr.fmt_hdr.sample_rate *
                                    wavehdr.fmt_hdr.nchan / 1000)
        {
            status = PJMEDIA_EWAVETOOSHORT;
            goto on_error;
        }
        
        /* Check compatibility of sample rate and ptime.
         * Some combinations result in a fractional number of samples per frame
         * which we do not support.
         * One such case would be for example 10ms @ 22050Hz which would yield
         * 220.5 samples per frame.
         */
        if (0 != (ptime * wavehdr.fmt_hdr.sample_rate *
                  wavehdr.fmt_hdr.nchan % 1000))
        {
            PJ_LOG(3,(THIS_FILE,
                  "Cannot create wav playlist port: incompatible sample "
                  "rate/ptime"));
            status = PJMEDIA_ENOTCOMPATIBLE;
            goto on_error;
        }

        /* It seems like we have a valid WAVE file. */
        
        /* Update port info if we don't have one, otherwise check
         * that the WAV file has the same attributes as previous files. 
         */
        if (!has_wave_info) {
            afd->channel_count = wavehdr.fmt_hdr.nchan;
            afd->clock_rate = wavehdr.fmt_hdr.sample_rate;
            afd->bits_per_sample = wavehdr.fmt_hdr.bits_per_sample;
            afd->frame_time_usec = ptime * 1000;
            afd->avg_bps = afd->max_bps = afd->clock_rate *
                                          afd->channel_count *
                                          afd->bits_per_sample;

            has_wave_info = PJ_TRUE;

        } else {

            /* Check that this file has the same characteristics as the other
             * files.
             */
            if (wavehdr.fmt_hdr.nchan != afd->channel_count ||
                wavehdr.fmt_hdr.sample_rate != afd->clock_rate ||
                wavehdr.fmt_hdr.bits_per_sample != afd->bits_per_sample)
            {
                /* This file has different characteristics than the other 
                 * files. 
                 */
                PJ_LOG(4,(THIS_FILE,
                          "WAV playlist error: file '%s' has differrent number"
                          " of channels, sample rate, or bits per sample",
                          filename));
                status = PJMEDIA_EWAVEUNSUPP;
                goto on_error;
            }

        }

        /* If file is shorter than buffer size, adjust buffer size to file
         * size. Otherwise EOF callback will be called multiple times when
         * file_fill_buffer() is called.
         */
        if (wavehdr.data_hdr.len < (unsigned)buff_size)
            buff_size = wavehdr.data_hdr.len;

        /* Create file buffer.
         */
        fport->bufsize = (pj_uint32_t)buff_size;        
        
        /* Set initial position of the file. */
        fport->fpos_list[index] = fport->start_data_list[index];
    }

    /* Fill up the buffer. */
    status = file_fill_buffer(fport);
    if (status != PJ_SUCCESS) {
        goto on_error;
    }
    
    /* Done. */
    
    *p_port = &fport->base;
    
    PJ_LOG(4,(THIS_FILE,
             "WAV playlist '%.*s' created: samp.rate=%d, ch=%d, bufsize=%uKB",
             (int)port_label->slen,
             port_label->ptr,
             afd->clock_rate,
             afd->channel_count,
             fport->bufsize / 1000));
    
    return PJ_SUCCESS;


on_error:

    if (fport->fd_list) {
        for (index=0; index<file_count; ++index) {
            if (fport->fd_list[index] != 0)
                pj_file_close(fport->fd_list[index]);
        }
    }

    if (pool)
        pj_pool_release(pool);

    PJ_PERROR(1,(THIS_FILE, status,
                 "Failed creating WAV playlist '%.*s'",
                 (int)port_label->slen, port_label->ptr));

    return status;
}


#if !DEPRECATED_FOR_TICKET_2251
/*
 * Register a callback to be called when the file reading has reached the
 * end of the last file.
 */
PJ_DEF(pj_status_t) pjmedia_wav_playlist_set_eof_cb(pjmedia_port *port,
                                void *user_data,
                                pj_status_t (*cb)(pjmedia_port *port,
                                                  void *usr_data))
{
    struct playlist_port *fport;

    /* Sanity check */
    PJ_ASSERT_RETURN(port, PJ_EINVAL);

    /* Check that this is really a playlist port */
    PJ_ASSERT_RETURN(port->info.signature == SIGNATURE, PJ_EINVALIDOP);

    PJ_LOG(1, (THIS_FILE, "pjmedia_wav_playlist_set_eof_cb() is deprecated. "
               "Use pjmedia_wav_playlist_set_eof_cb2() instead."));

    fport = (struct playlist_port*) port;

    fport->base.port_data.pdata = user_data;
    fport->cb = cb;

    return PJ_SUCCESS;
}
#endif


/*
 * Register a callback to be called when the file reading has reached the
 * end of the last file.
 */
PJ_DEF(pj_status_t) pjmedia_wav_playlist_set_eof_cb2(pjmedia_port *port,
                                void *user_data,
                                void (*cb)(pjmedia_port *port,
                                           void *usr_data))
{
    struct playlist_port *fport;

    /* Sanity check */
    PJ_ASSERT_RETURN(port, PJ_EINVAL);

    /* Check that this is really a playlist port */
    PJ_ASSERT_RETURN(port->info.signature == SIGNATURE, PJ_EINVALIDOP);

    fport = (struct playlist_port*) port;

    fport->base.port_data.pdata = user_data;
    fport->cb2 = cb;

    return PJ_SUCCESS;
}


/*
 * Get frame from file for file_list operation
 */
static pj_status_t file_list_get_frame(pjmedia_port *this_port,
                                       pjmedia_frame *frame)
{
    struct playlist_port *fport = (struct playlist_port*)this_port;
    pj_size_t frame_size;
    pj_status_t status;

    pj_assert(fport->base.info.signature == SIGNATURE);

    //frame_size = fport->base.info.bytes_per_frame;
    //pj_assert(frame->size == frame_size);
    frame_size = frame->size;

    /* Copy frame from buffer. */
    frame->type = PJMEDIA_FRAME_TYPE_AUDIO;
    frame->size = frame_size;
    frame->timestamp.u64 = 0;

    if (fport->readpos + frame_size <= fport->buf + fport->bufsize) {

        /* Read contiguous buffer. */
        pj_memcpy(frame->buf, fport->readpos, frame_size);

        /* Fill up the buffer if all has been read. */
        fport->readpos += frame_size;
        if (fport->readpos == fport->buf + fport->bufsize) {
            fport->readpos = fport->buf;

            status = file_fill_buffer(fport);
            if (status != PJ_SUCCESS) {
                frame->type = PJMEDIA_FRAME_TYPE_NONE;
                frame->size = 0;
                return status;
            }
        }
    } else {
        unsigned endread;

        /* Split read.
         * First stage: read until end of buffer.
         */
        endread = (unsigned)((fport->buf+fport->bufsize) - fport->readpos);
        pj_memcpy(frame->buf, fport->readpos, endread);

        /* Second stage: fill up buffer, and read from the start of buffer. */
        status = file_fill_buffer(fport);
        if (status != PJ_SUCCESS) {
            pj_bzero(((char*)frame->buf)+endread, frame_size-endread);
            return status;
        }

        pj_memcpy(((char*)frame->buf)+endread, fport->buf, frame_size-endread);
        fport->readpos = fport->buf + (frame_size - endread);
    }

    return PJ_SUCCESS;
}


/*
 * Destroy port.
 */
static pj_status_t file_list_on_destroy(pjmedia_port *this_port)
{
    struct playlist_port *fport = (struct playlist_port*) this_port;
    int index;

    pj_assert(this_port->info.signature == SIGNATURE);

    if (fport->subscribed) {
        pjmedia_event_unsubscribe(NULL, &file_on_event, fport, fport);
        fport->subscribed = PJ_FALSE;
    }

    for (index=0; index<fport->max_file; index++)
        pj_file_close(fport->fd_list[index]);

    if (fport->pool)
        pj_pool_safe_release(&fport->pool);

    return PJ_SUCCESS;
}

